SEOUL, South Korea — North Korea's army said Monday it is ready to "blow up" South Korea and the U.S., hours after the allies kicked off annual military drills that Pyongyang has slammed as a rehearsal for attack.

South Korea and the U.S. — which normally dismiss such threats as rhetoric — began 11 days of drills across South Korea on Monday morning to rehearse how the U.S. would deploy in time of emergency on the Korean peninsula.

The U.S. and South Korea argue the drills — which include live firing by U.S. Marines, aerial attack drills and urban warfare training — are purely defensive. North Korea claims they amount to attack preparations and has demanded they be canceled.

The North's People's Army issued a statement Monday, warning the drills created a tense situation and that its troops are "fully ready" to "blow up" the allies once the order is issued.

The North also put all its soldiers and reservists on high alert to "mercilessly crush the aggressors" should they encroach upon the North's territory even slightly, said the statement carried by the official Korean Central News Agency.

The communist country has issued similar rhetoric in the days leading up the drills. On Sunday, it said it would bolster its nuclear capability and break off dialogue with the U.S. in response to the drills.

South Korea's military has been closely monitoring Pyongyang's maneuvers but hasn't seen any signs of suspicious activities by North Korean troops, Seoul's Joint Chiefs of Staff said earlier Monday.

About 20 anti-U.S. activists held a peaceful protest near a joint drill command center south of Seoul on Monday, chanting slogans such as "Stop war rehearsal."

About 18,000 American soldiers and an undisclosed number of South Korean troops are taking part in the drills, dubbed Key Resolve and Foal Eagle, according to U.S. and South Korean militaries.

The training comes as the U.S. and other regional powers are pushing for the North to rejoin international disarmament talks on ending its atomic weapons program in return for aid. The North quit the six-nation weapons talks and conducted its second nuclear test last year, drawing tighter U.N. sanctions.

The North has demanded a lifting of the sanctions and peace talks with the U.S. on formally ending the Korean War before it returns to the negotiations. The U.S. and South Korea have responded that the North must first return to the disarmament talks and make progress on denuclearization.